Topic: Localization and the Neuropsychology of Motivation, Emotion and Social Cognition

Essay: "The principle of functional specialization which is apparent in visual cortex applies to affective states and social cognition as well." Discuss.

The issue of localization is sometimes addressed as specific to cognitive functions, visual and somatosensory perception in particular. The kind of questions about the functional specializations of different brain structures or regions can also be asked about motivation and emotion, although there may be differences of emphasis.

Indeed the variety of topics addressed in brain imaging studies in recent years suggests that the original single neuron doctrine of Barlow (1972), which was formulated in the context of

'a simple correspondence between the elements of perception and unit activity' could now be expressed in terms of

'a simple correspondence between the elements of any psychological state and activity in identified neurons'.

Berman et al., (2006) noted that while in 1993 fewer that 20 papers were published reporting the use of fMRI, there were nearly 1800 such papers in 2003 and the range of psychological topics studied has vastly expanded over the same period.

.

[middle of page 1 of handout]

i. Emotion

There is not universal agreement about a clear distinction between cognitive and affective processes.
Pankseep
(2003) lists 6 overlapping characteristics which he argues
distinguish affective states from cognitive processes:

affective
states have valence (they are accompanied by positive or negative
feelings);

cognitions are
generated by a digital style of information processing, whereas
emotions are influenced by analogue neurohormonal factors

emotions
but not cognitions are associated with spontaneous transcultural
facial expressions; and

the right hemisphere is more emotional,
and concentrates on negative emotions whereas the left hemisphere is
linguistic and analytical yet more prone to positive emotions.

Pankseep (2003) accepts that his is a minority view, and that others have argued against any distinction between cognitive and emotional processes, but there would be general agreement that the brain circuits involved in emotional regulation are distinctively different from those required by cognitive information processing (Rolls, 2000; Cardinal et al, 2002)

[bottom of page 1 of handout]

Broadly, emotion and motivation are dealt with by the limbic system together with associated midbrain and frontal lobe regions (see p. 6).

For human brain scanning studies, orbitofrontal (sometimes called prefrontal) cortex is of particular interest. Kringlebach and Rolls (2004) proposed two distinct trends of neural activity based on a review of brain-imaging studies.

The first is a distinction between medial and lateral areas, with the medial orbitofrontal areas being activated by positive or rewarding stimulus and lateral areas responding to negative or punishing outcomes.The second is a posterior-anterior difference, (within the orbitofrontal region) with more abstract outcomes (such as monetary gain or loss) being represented anteriorly, and more direct pleasurable outcomes such as taste or pain, posteriorly. (e.g. Small et al, 2001; Knutson et al, 2001)

However, limbic structures, such as the amygdala and cingulate gyrus, are also often detected in brain imaging studies as well as the reward pathway starting in the midbrain ventral tegmental area (often abbreviated VTA) going via the medial forebrain bundle to the nucleus accumbens in the basal ganglia (see p. 6) as well as the prefrontal emotionally sensitive areas.

This reward pathway was first identified in the 1950s by investigations of self-stimulation via implanted electrodes in rats and there is continued interest in these areas because of their involvement in addiction (Berridge, 2003; Robinson and Berridge, 2003; Ikemoto and Wise, 2004; Volkow et al, 2004).

[top of page 2 of handout]

Three recent review papers include accounts of the neural structures underlying emotions.

Kavanagh et al. (2005) present an elaborate cognitive theory of human desire, but the theory has its roots as an explanation for cravings for psychoactive substances, and it identifies the "mesocorticolimbic dopamine pathway" as important for incentives considered very generally.

Lewis (2005) presents psychological model of self-organizing emotional interpretations based on dynamic systems theory, but also wants to identify different components of emotional appraisal - perception, evaluation, attention, memory, and planning/reflection - with different neural systems and includes several circuit diagrams of feedback circuits involving the VTA (Ventral Tegmental Area), the amygdala, orbitofrontal cortex, anterior cingulate cortex and so on.

Phelps (2006) reviews 5 topics: emotional learning, emotion and memory, emotional influences on attention, emotional effects of social stimuli, and change in emotional responses, all in terms of the functions of the human amygdala.

Much of the evidence linking the mesocorticolimbic structures to motivation and emotion is based on physiological studies with monkeys or rats, but human brain imaging experiments provide some degree of confirmation that extrapolations to humans are justified.

[middle of page 2 of handout]

Bartels and Zeki (2000) and Aron et al., (2005) recruited subjects who were deeply in love, and compared fMRI scans when these subjects were looking either at pictures of their partners or control pictures of friends or familiar individuals. Bartels and Zeki (2000) found activity in the anterior cingulate cortex and in the basal ganglia associated with viewing partners. These structures have been implicated in other kinds of emotion but the precise location and pattern of activity lead the authors to suggest that a unique network was involved, and thus postulated "that the principle of functional specialization in the cortex applies to affective states as well". Aron et al found a somewhat similar pattern of activation, with anterior cingulate activity correlating with length of the romantic relationship, but they also found activation in the ventral tegmental area, with a suggestion that this is lateralized on the right, but nevertheless draw an opposing conclusion, namely "that romantic love does not use a functionally specialized brain system" because of the generic nature of the mesocorticolimbic incentive network.

ii. Social cognition and other areas of human psychology

Amodio and Frith (2006) and Saxe (2006) offer general reviews of evidence about the brain circuits involved in social cognition, in which areas in the frontal lobes figure prominently.

Goldberg et al (2006) claim a complete segregation between patterns of brain activity produced during self-reflective introspection and a sensory categorization task and Northhoff et al. (2006) review a large collection of imaging studies of the self which locate it in 'cortical midline structures'.

Conclusion: there is localization of function in the brain systems that subserve motivation and emotion, and related areas of psychology such as social cognition and decision making, in the sense that detailed circuits of named structures are involved and imaging studies are able to show specific patterns of activation associated with specific emotions. However, the level of detail of localization, and the current understanding of functional specializations in the areas involved, is considerably less developed than is the case for the visual system

Ikemoto, S., & Panksepp, J. (1999). The role of nucleus accumbens dopamine in motivated behavior: a unifying interpretation with special reference to reward-seeking. Brain Research Reviews, 31(1), 6-41.